1. Field of the Invention
The invention relates to smart cards, and particularly communication processes between a smart card and an external unit.
Smart cards are becoming a widely used support to contain and transfer different types of information, particularly for bank transactions, transport tickets, health information and for identification. Smart cards are usually stored in a plastic card, like a bank card. These cards usually contain a memory and a processor intended for storage and processing of data. The smart card is conventionally inserted into a card reader that makes an electrical contact with electrical contacts of the card.
2. Discussion of the Related Art
ISO standard 7816 defines the characteristics of the most widely used smart cards. This standard is thus used to define the characteristics of SIM cards or bank cards. ISO standard 7816-2 defines the number, function and position of electrical contacts on the surface of the chip with a connected interface. The English version of ISO standard 7816-2 calls these contacts “pins”. Surface pins are denoted C1 to C8 in this standard. Pin C1, also denoted Vcc, is used to make a power connection through which the chip on the card is supplied with power. Pin C2, also referred to as RST or Reset, transmits an external command signal initiating a chip reinitialization instruction sequence. Pin C3, also denoted CLK, transmits a clock signal to the chip. Pin C5, also denoted GND, provides an electrical ground common to the integrated circuit of the chip and the device connected to the chip. Pin C6, also called Vpp, is used to program an EEPROM on the chip if there is one. Pin C7, also called the I/O pin, provides a communication channel between the connected device and the chip. ISO standard 7816-2 has not yet assigned any use to pins C4 and C8.
ISO standards 14443 and 15693 propose to include a passive antenna in the card so as to communicate with an external device by radio frequency.
ISO standard 14443 in particular defines a radio-frequency communication protocol that ideally can communicate at up to 20 centimeters from the antenna. However the communication distance provided by the antenna is limited. The communication speed is also limited by the modulation frequency.
ISO standard 15693 describes another communication protocol to communicate at a greater distance than with ISO standard 14443, but with a lower communication speed. The communication distance supplied is still relatively small.
In general, antennas of these smart cards have a limited range. Furthermore, their range is strongly affected by their environment. In general, the presence of metallic parts (particularly a battery or other electrical circuits of a device in which the card is placed) deteriorate the range of the card. Furthermore, some small cards (for example a SIM card) cause lower antenna performance.
Therefore there is a need for a communication process, a smart card and equipment solving one or several of these problems, and the invention is intended to satisfy this need.